option solver minos;
var p1>=0, <=1;
var p2>=0, <=1;
var p3>=0, <=1;
var p4>=0, <=1;
minimize obj: -1+-0.9*p3;
subject to r1:  p1>=0.100000;
subject to r2:  p1<=0.300000;
subject to r3:  p2>=0.100000;
subject to r4:  p2<=0.300000;
subject to r5:  p3>=0.300000;
subject to r6:  p3<=0.500000;
subject to r7:  p4>=0.500000;
subject to r8:  p4<=0.700000;
solve;
print 'p1',p1;
print 'p2',p2;
print 'p3',p3;
print 'p4',p4;
